Carburetor control



March 8, 1938. J, FARRELL 2,110,211

CARBURETOR CONTROL Filed May 20, 1952 2 Sheets-Sheet 1 INVENTOR.

James /'?//z// lub a zw March 8, 1938. J, p FARRELL 2,110,211

CARBURETOR CONTROL Filed May 20, 1952 2 Sheets-Sheet 2 5,; j /jm ATTORNE YS.

Patented Mar. 8, 1938 'NI'TED' STATES PATENT OFFICE 2,110,211 cennonnroncoN'rnoL James P. Farrell, Berkeley, Calif.

Application May 20, 1932, Serial No. 612,533

15 Claims.

My invention relates to means for controlling a carburetor used inconjunction with an internal combustion engine and is especially usefulin conjunction with carburetors on automotive vehicles:

Itis customary in starting an internal combustion engine from cold toreduce materially the proportion of air in the fuel-air mixture, andafter the engine has arrived at operating temperature to restore theproportions to their running values. An engine after having been startedand while still cold can only with great diiiiculty be idled or runslowly, partly because of the added friction due to viscous oil and alsobecause of various other factors. If the proportion of air and fuel isvery carefully regulated, a cold engine can nevertheless be runrelatively slowly or alternatively if the air-fuelvmixture is notprecisely regulated then the engine must be run somewhat faster.

It is therefore an object of my invention to provide an automatic meansfor permitting an engine to run relatively rapidly when cold.

Another object of my invention is to provide a mechanism which willcause an engine to run relatively rapidly when cold but which willpermit the engine to run relatively slowly when it has arrived at itsoperating temperature.

A further object of my invention is to provide a speed regulatingmechanism on a carburetor which is self-contained and is independent ofthe customary throttle linkage and closure springs.

The foregoing and other objects are attained in the embodiment of theinvention shown in the drawings, in which- Figure 1 is a cross sectionon a dlametral plane of a carburetor throat with the carburetor controlof my invention incorporated therewith.

Figure 2 is a cross section the plane of which is indicated by the line22 of Figure 1.

Figure 3 is a plan of a modified form of carburetor control inaccordance with my invention.

Figure 41s a cross section, the plane of which is indicated by the lines4-4 of Figure 3.

Figure 5 is a cross section on a dlametral plane of a still furthermodified form of carburetor control of my invention.

Figure 6 is a plan of a different form of control suitable for use withthe carburetor of Figure 1.

Figure 7 is a side elevation of the mechanism shown in Figure 6.

Figure 8 is a cross section on an axial plane of a different form ofcarburetor control of my invention.

Figure 9 shows the mechanism of Figure 8 in a different position.

Figure 10 shows the mechanism of Figure 8 in another position.

Figure 11 shows the throttle valve of Figure 8 in plan. 1

In its preferred form, the carburetor control of my invention is adaptedto be used in conjunction with a carburetor adapted to furnish a fluidfuel mixture and which is provided with a valve for preventing flow ofsaid mixture, and includes means for permitting an auxiliary flow undercontrol of a thermostat.

In the form of the device disclosed in Figures 1 and 2 there isillustrated part of the induction mechanism of an engine, in thisinstance a portion of a standard carburetor having a cylindrical wall 6defining a carburetor throat I through which a combustible fuel mixtureis designed to flow in the direction of the arrow 8. The pressureadjacent the arrow 8 is considerably higher than the pressure in theregion 9 and causes the flow through the throat I. The wall 8 mergesinto a flange ll provided with suitable apertures I2 for the receptionof fastening devices for securing the carburetor to the manifold of theengine with which the device is utilized.

In order to control flow through the throat 7, bosses I 4 and I8 formedintegrally with the wall are pierced by a throttle shaft l3 on which ismounted a butterfly valve or disc 11, and at one end of which is a leveri 8 designed to be connected to the usual throttle operating linkage.Such linkage customarily is manually or pedally impelled in onedirection to move the disc I! to open or non-obstructing position, andis returned to move the disc to closed or obstructing position by meansof a relatively stiff and powerful spring. Because of such spring I havefound it impractical to provide a mechanism for holding the throttleshaft I3 in slightly open position to give faster idling speeds when theengine is cold.

In lieu of such an arrangement and as an improvement thereover, Ipreferably pierce the disc I! with a plurality of conduits or passagesl9 which permit flow from one side of the disc to the other by virtue ofthe difference in pressure and further provide a thermostat 2| so thatflow can occur freely through the apertures or conduits I9 when theengine is cold, but will be prevented when the engine is warm.

In the present instance, the thermostat is comprised of a bimetallicdisc including a first metal sheet 22 and a second metal sheet 23 havingdifferent coefflcients of expansion. Since thesesheets are united, underthe influence of varying temperature, they snap quickly from one extremeposition to a second extreme position through a a median planar posi on.In order that the disc 2| can suitably be he I preferably pass a bolt 24through the throttle shaft l3 and through the disc 2| and the. butterflyvalve H. The bolt is retained by a suitable nut 26 and, if desired, awasher 21 can be interposed between the disc 2| and the throttle shaft|3. Withthis arrangement, when the parts are relatively cold the disc 2|assumes the position shown in Figure 1, permitting ample idling flowthrough the-conduits or apertures l9, despite the fact that the mainbutterfly valve may be in closed position. As the temperature increasesdue to continued operation of the engine, at a critical value the disc2| snaps into its other extreme position closely'overlying theaperturesor conduits l9 and thus acting as a valve to prevent flowtherethrough, and thus confining the flow of mixture past the butterflyvalve disc I! simply to the leakage thereby. There is thus provided amechanism which automatically permits-a greater flow of combustiblemixture past the butterfly valve when the parts are cold than ispermitted when the parts are warm.

I have found in practice that it is usual for -the wall 6 of thecarburetor throat to expand much differently under variations intemperature than the butterfly valve disc I8 and thus to cause erraticoperation, especially erratic idling. To overcome this deficiency Ipreferably counterbore thecarburetor throat wall 6 and insert therein asleeve 21 of material such as inv-ar. The throttle disc I! is then alsomade of inv'ar. Since these parts are of the same material and are of amaterial which has a relatively low coefllcient of expansion, theclearance between the throttle disc I! and the wall of the throat I ismaintained substantially constant.

In the event that pulsations and fluctuations in pressure within thethroat 1 are sufficient to ing the valve to a throttle shaft such as I3.

cause deleterious and audible vibration of the disc 2|, I preferablyemploy in place thereof a mechanism including a balanced valve whichinherently is not subject to disturbance by pressure pulsations orfluctuations. As shown in Figures 3 and 4, there is provideda mainbutterfly valve'or disc 28 which is formed with a central aperture 29for the reception of a fastening means for secur- The disc is likewisepierced by acircular aperture 3|, through which, whenthe aperture isunobstructed, an auxiliary mixture flow can occur. Mounted on suitabletrunnions 32 and 33 flxed on the disc 28 is a cross shaft 34 carrying abalanced disc valve 36. The valve is provided with a pitman 39, pivotedthereto, as at 4|, which is likewise pivoted as at 42 to the freeextremity of a bimetallic thermostatic strip 43. This strip is anchoredto the. disc 28 by suitable fastening means 44.

In this arrangement when the parts are rela-. tively cold thethermostatic strip 43 maintains the valve disc 36 substantially in theposition A shown in Figure 4, permitting considerably auxiliary flowthrough the aperture 3|. As the parts increase in temperature, the strip43 through the medium of the pitman 39 rocks the disc 36 from theposition "A into a position B in which the disc is coplanarwith thebutterfly disc 23, and flow through the aperture 3| is substantiallyprevented.

After an engine has arrived at operating temperature and has been shutdown, fuel flow through thethroat of the carburetor has ceased,

but heat radiates thereto from the surrounding parts and causes afurther increase in temperature of the thermostatic strip 43. Suchadditional increase in temperature causes a movement of the disc 3| intoa position such as C. Inthis position flow through the aperture 3| isagain permitted, so that if the engine is again started.

during the period of increased temperature con siderable auxiliarymixture is permitted to flow for starting purposes. As soon as amaterial flow of air and particularly 'of cold gasoline or other fuelstrikes the thermostatic strip 43, the disc 36 is immediately drawn toposition 13" and prevents further auxiliary flow.

In installations in which it is not desirable to mount the mechanismdirectly on the butterfly throttle valve itself, I preferably providethe structure shown in Figure 5, in which the wall 46 of the carburetorthroat 41 isv provided with a relatively small passage 33 shunting thebutterfly.

; passage ofan auxiliary flow of mixture around the butterfly valve 49,even through the latter valve. is in closed position, However, when theparts are relatively warm the thermostatic strip 56 operates to closethe valve 5| and to preclude further flow through the passage 36.

In the form of my invention disclosed in Figures 6 and '7, a throttledisc 6| is provided with a thermostatic strip 62 at one end anchored toa bracket 63 mounted on the throttle disc and at the other end carryinga plate valve 64 adapted to overlie an elongated aperture66 piercing thedisc 6|. When the parts are relatively warm the plate 64 fully overliesthe aperture 66 and precludes auxiliary flow therethrough, while whenthe parts are relatively cold the thermostatic strip 62 moves in such afashion as touncover part or all of the aperture 66 and to permitauxiliary mixtur flow therethrough.

In all of the forms of my device in which the thermostatic element ismounted on the throttle disc itself, it is usually preferable to mountthe strip on the high pressure side of the throat so that the incomingstream of air .or air and fuel which is relatively cool can maintain thethermostat at a relatively low temperature. Under certain conditions,however, successful results have been obtained by mounting thethermostatic element on the low pressure side of the disc where it issomewhat protected from the incoming stream of fuel mixture.

It is often advisable to provide a mechanism which can be installed instandard carburetors without substantial change thereof, but which willnevertheless be suitable for installation in new designs of carburetors.Such mechanism is disclosed in Figures 8 to 11, inclusive. As showntherein, there is provided a conduit which, for example, is a carburetorthroat defined by a wall 1| having flanges I2 thereon pierced byapertures 13 for the reception of fastening devices for securing themechanism to a suitable support. In the customary way, mixture flowsthrough the passage 14 defined by the wall 1| and is preferablycontrolled by a throttle or butterfly valve,

generally designated 18. This throttle is preferably mounted on athrottle shaft 11 which is suitably journalled in the wall Ii. Rotationof the throttle shaft moves the throttle valve 16 to govern the flowthrough the conduit 14. As shown in Figure 8, the throttle disc, when ona slight incline, abuts the wall H throughout its entire periphery andsubstantially closes the passage N. I

In order that there can be an auxiliary flow through the passage II whenthe engine to which the carburetor control is attached is relativelycold, to increase the idling speed automatically, I preferably fabricatethe valve 16 in the form of discs 18 and 19 which are composed of twometals having widely diiferent coefflcients of expansion. Preferably,the metal of the disc 19 is invar, while the metal of the disc I8 isbrass, for instance. In order that the difference in expansion rates ofthese metals will be relatively ineffective in the direction of the axisof the shaft 11, I preferably sever the sheet 78 into a multiplicity ofstrips by a plurality of parallel cuts 8|, as disclosed in Figure 11.

Because of this construction, when the engine is relatively cold thebrass disc 18 is somewhat shorter than the invar disc 19 in thedirection of the cuts BI, and therefore causes the valve 16 to take theshape shown in Figure 9, allowing a slight passage between the edge ofthe valve and the wall II. It is to be understood that Figures 9 and areboth greatly exaggerated, inasmuch as only a small clearance between thevalve and the wall H is required and obtained. On the other hand, whenthe engine is in normal operating condition, the valve 16 issubstantially as shown in Figure 8. Just after the engine has been runand has been shut down, additional heat radiates to the valve 16. Thisheat is not dissipated since there is no cooling flow of air andgasoline, so that the temperature of the valve 16 continues to increase.The valve then flexes in a direction to make an additional opening asshown in Figure 10, which assists momentarily in a subsequent start ofthe engine.

I claim:

1. A carburetor control comprising a carburetor throat through which afuel mixture flows, a butterfly valve adapted when closed to preventflow through said throat, said butterfly valve having a conduittherethrough, a valve movable with said butterfly valve for controllingflow through said conduit, and thermostatic means for actuating saidvalve.

2. A carburetor control comprising a carburetor throat through which afuel mixture flows,

Y a butterfly disc adapted when closed to prevent flow through saidthroat, said disc having a fuel mixture passage therethrough, andtemperature responsive means movable with said disc for controlling flowthrough said passage.

3. A carburetor control comprising a carburetor throat through which afuel mixture flows, a butterfly disc adapted when closed to prevent flowthrough said throat, said disc having a fuel mixture passagetherethrough, and a thermostat stat mounted on said butterfly disc foractuating said valve.

5. A carburetor control comprising a carburetor throat through which afuel mixture flows, a butterfly disc adapted when closed to prevent flowthrough said throat, said disc having a fuel mixture passagetherethrough, a valve movable with said disc for controlling flowthrough said passage, and a thermostat adapted to open said valve inresponse to a relative- 1y low temperature and to close said valve inresponse to a relatively high temperature.

6. A carburetor control comprising a carburetor throat through which afuel mixture flows, a butterfly disc on opposite sides of whichdifferent pressures exist and adapted when closed to prevent flowthrough said throat, said disc having a fuel mixture passagetherethrough, a. valve unaffected by said diflerent pressures forcontrolling flow through said passage, and a thermostat mounted on saidbutterfly disc and adapted to open said valve in response to arelatively low temperature and to close said valve in response to arelatively high temperature.

7. A carburetor control comprising a carburetor throat through which afuel mixture flows, an operating shaft spanning said throat, a throttledisc fixed on said shaft, and thermostatically controlled means entirelysupported by said disc for lessening the eifective area of said disc.

8. A carburetor control comprising a carburetor duct through which fuelmixture flows, a transverse shaft spanning said duct, a butterfly valveon said shaft and adapted to be moved from a flow restricting positionin close proximity to the walls of said duct to an open position remotefrom the walls of said duct, and thermally-controlled means unaffectedby the proximity of said valve to said walls of said duct for conductingfluid from one side of said butterfly valve to the other side thereof.

9. A carburetor control comprising a carburetor duct through which fuelmixture flows, a, butterfly valve relatively movable in said duct andadapted by its relative position in said duct to control fluid flowtherethrough, means including a passage the cross sectional area ofwhich isindependent of the relative position of said butterfly valve forconducting fluid from one side of said butterfly valve to the other sidethereof, and thermally responsive means for controlling said conductingmeans.

10. A carburetor control comprising a carburetor duct, a fuel mixturethrottling valve therein, said throttling valve having a passagetherein, a valve carried by said throttling valve and co-operating withsaid passage, and temperature responsive means for controlling saidvalve.

11. A carburetor control comprising a carburetor duct, an operatingshaft spanning said duct, 2. fuel mixture throttling valve on saidshaft, means supported entirely by said operating shaft for lesseningthe effective area of said throttling valve, and thermally responsivemeans for controlling said lessening means.

12. A carburetor control comprising a carburetor passage through which afluid flows, a butterfly valve adapted when closed substantialterflyvalve having a conduit therethrough, a substantially balanced valvemovable with said butterfly valve for controlling flow through saidmeans forming a passage having walls which are fixed relative to eachother for conducting fluid fromone side of said butterfly valve to theother side thereof, and a temperature-responsive valve for controllingsaid pasage.

15. A carburetor control comprising a car buretor passage through whicha fuel mixture flows, a butterfly valve in said passage for controllingflow .therethrcugh, a conduit having walls which are fixed relative toeach other shunting said butterfly valve, and thermostatic mans forvarying the eflective area of said con- JAMES P. FARRELL.

